1. Field of the Invention
The present invention relates to a medical guiding system, a medical guiding program, and a medical guiding method, for guiding a medical instrument using a medical image.
2. Description of Related Art
When performing ultrasonic endoscopy or laparoscope surgery, an operator performs diagnosis and surgery, assuming anatomical position under current observation, while preconceiving known anatomical relational positions of viscera or organs in a living body. To assist such diagnosis and surgery, there have been proposed techniques for displaying a guiding image for guiding a position under observation in inspection and surgery, through synthesis based on a CT image and MRI image obtained in advance.
As an example of such a medical guiding apparatus, Japanese Patent Application Laid-Open No. 10-151131 describes a medical guiding apparatus that detects the position of an ultrasonic probe, obtains from image data a tomographic image corresponding to a tomographic position of an ultrasonic image, and then displays the obtained tomographic image and the ultrasonic image in juxtaposed, superposed, or constant-interval alternate manner.
Further, Japanese Patent Application Laid-Open No. 2005-312770 describes a medical guiding apparatus that detects a distal end position of an ultrasonic endoscope, constructs a guiding image corresponding to an anatomical position of the ultrasonic endoscope based on anatomical image data, and displays the constructed image.
Still further, Japanese Patent Application Laid-Open No. 2004-113629 describes a technique that detects a position and orientation of a scanning surface of an ultrasonic probe, so as to display an accurate guiding image.
In addition, Japanese Patent Application Laid-Open No. 2002-345725 describes a medical guiding apparatus that displays a three-dimensional model image corresponding to a distal end position of an endoscope, by generating a three-dimensional viscus model image from medical image data obtained by prephotographing, further sequentially correcting the three-dimensional viscus model according to fluctuation amount of the viscus per unit time, and then detecting the position of the distal end of the endoscope.
By the way, in CT and MRI for obtaining image data in advance (prior to using a medical instrument), a subject is usually photographed in a supine position. In contrast, inspection, surgery, and so forth, using a medical instrument such as an endoscope and an ultrasonic endoscope, are performed with the subject in a left lateral or prone position. However, because the gravitational direction with respect to the body is different between the supine position and the left lateral or prone position, positional relations of viscera and blood vessels in a body cavity would be subject to change. Therefore, a guiding image produced for an image obtaining position in performing endoscopy, based on a CT or MRI image photographed with the subject in the supine position, would be different from an endoscopic or ultrasonic image obtained in endoscopy, in terms of positions of viscera in the body cavity.
The above-mentioned situation occurs not only in the above case but also when using a laparoscope or an extracorporeal ultrasonic diagnostic apparatus, if the subject is not in the supine position.
Moreover, when, for example, performing tissue sampling in narrow bronchia disallowing insertion of an endoscope, by inserting a treatment instrument or the like into a bronchial endoscope channel, it is necessary to make a distal end position of the treatment instrument reach a tissue sampling location while observing only the above-described guiding image, since endoscopic image observation can not be performed. Accordingly, in a case like this, a highly accurate guiding image is required that eliminates a deviation between actual position of the treatment instrument and position thereof in the guiding image.